My Pichu JUST Hatched And It Knows: ![][1]-![][2]
Pichu @Sooth Bell Lv.6 (Obviously In Training.) Trait: Static Nature: Adamant (+Atk. -Sp.Atk.) EV's: Unknown At The Moment...
How Does It Know This? [1]: http://static.gamesradar.com/images/mb/GamesRadar/us/Daily/2010/08-Aug/02/Top 7 births/Egg--article_image.jpg [2]: http://images1.wikia.nocookie.net/rosepichu/images/5/5f/Shinypichu2.png
it knows thunder and iron tail because the male pokemon you where breeding knows those two moves and pichu can learn them through tms.
hope I helped!
Most likely they were egg moves passed down from the father. Who did you breed?
Egg Moves from your Pikachu/Raichu. Simple as that.
Because those are moves pichu can learn. And because one of the Parents probably knew those moves it was passed down to pichu. simple as that